Reference is hereby made to co-pending applications:
______________________________________ Serial Number Filing Date ______________________________________ 658,698 February 17, 1976 854,615 November 25, 1977 864,707 December 27, 1977 864,706 December 27, 1977 864,708 December 27, 1977 ______________________________________
The general purpose is to provide a heat retaining magma which is electrically heated e.g. during off peak hours, the heat being retrieved later for the purpose of providing steam for making additional electricity. These magmas may be used for other purposes requiring or benefiting from heat storage also.
In general the electricity traverses the brick heating the same due to the resistance of the bricks to passage of the electricity therethrough, and it is necessary to provide an electric contact placing the brick (or bricks) in circuit.
This has been found to present some difficulities due to the fact that the bricks are pitch bonded and are molded of discrete material comprising originally e.g. aluminum or magnesium oxide, intersperced with particles of carbon, it being preferred that the carbon particles be greater in number in the areas where the electricity is applied to the bricks.
An efficient way to provide for electricity to pass into a brick is to provide a hole to receive a bolt of electricity conducting material and to apply the electric contact or electrode thereto. The bolt may, as a matter of fact, be molded directly into the brick when the brick is made.
However, the material of the brick and the material of the bolt have different co-efficients of expansion under conditions of heat and thus at times the bolt will be relatively lose compared to the hole in which it is located in the brick. In any event, the brick being originally made of discrete particles, has a relatively rough surface including pits and, of course, this increases the resistance of the electricity in its passage from the bolt into the brick, tending to heat the brick to an undesired degree at the area of the junction of the bolt and the brick.
It is the object of the present invention to provide a construction which insures an extremely good contact between the brick and the bolt or other electrode to allow for different rates of expansion of the parts while still maintaining intimate contact, and also to cure the increased resistance due to pits and in some cases cracks and crumbling of portions of the bricks under conditions of use.
Although the graphitic sheets which are a part of the inventive concept in the present invention are old and well-known and are commercially available, being manufactured by Union Carbide Company, applicant is not aware of any prior art according to the present invention, the closest being his own co-pending application.
This application shows the use of semi-flexible graphitic sheets interposed between electrodes and the surface of the brick, etc., or between faces of two adjacent bricks, which improves the electric contact between the parts and insures good conductivity, obviating unwanted build up of heat at the electric contact area of the contiguous brick.